Tamerlan and Dzhokhar Tsarnaev detonated two pressure cooker bombs in a crowd at the 2013 Boston Marathon. We try to understand what caused them to do this.

In January 2005, Neil Olsen was found dead in his barn. Murdered. His wife, Patricia Olsen, was adamant that Neil's horse was the murderer.

Modern day mass shootings trace their roots back to this event. On Aug.1, 1966, Charles Whitman set himself up at the tower at University of Texas - Austin, and shot anyone he could.

Jolly Jane, the original Incel. She was a nurse who drugged her patients in order to sexually assault them. Here's to you Bill Cosby. By her own account, she also poisoned and murdered over 100 people.

More on Richard Kuklinski, the psychopath killer known as The Iceman.

Richard Kuklinksi was the epitome of a cold-blooded killer. Murder was both a hobby and a profession for him. He claims to have killed as many as 200 people.

Britney Spears has been victimized by a conservatorship system run amok and has had her freedom taken away. Bill Cosby on the other hand has raped many women and is totally free. Nice job US legal system.

Vanessa Marcotte was a smart, successful young woman, with a great career, great family great life. It all ended one day while she was out for a run in the very safe town of Princeton, MA.

Skylar Neese was a teenager with a bright future ahead of her, but it was brutally ended by her best friends, Shelia Eddy and Rachel Shoaf.

Theresa Corley was a lovely young woman, with a promising life ahead of her. Then, in December 1978 she was raped and murdered. Her sister, Geri, has spent decades trying to get justice for her sister. Geri talks with us about the murder and the botched investigation.